1. Field of the Invention
The present invention relates to a hydraulic orifice, and more particularly to a hydraulic orifice which reduces pulsation of an oil supplied to a variable valve apparatus of an engine.
2. Description of Related Art
Generally, oil pressurized at a hydraulic pump passes through a hydraulic line in a cylinder block and is supplied to a cylinder head. Finally, the oil is supplied to various variable valve apparatuses through an oil control valve.
A head oil journal is formed between the cylinder block and the cylinder head of the engine, and a hydraulic orifice is mounted at the head oil journal such that a flow direction, a pressure, and a pulsation of the oil received from the hydraulic pump are controlled and the controlled oil is supplied to the oil control valve.
A conventional hydraulic orifice is mounted at a head oil journal formed in a cylinder head, and supplies oil received from a hydraulic pump to a supply line.
The hydraulic orifice includes an outer case and an inner case, the outer case is pressed on the head oil journal, and the inner case is pressed on an interior circumference of the outer case. At this time, a forming portion formed at the outer case is bent toward the inner case so as to assemble the inner case to the outer case.
An inner chamber is formed in the inner case. In addition, an oil hydraulic line for connecting the inner chamber with the supply line is formed at an exterior circumference of the inner case. The oil hydraulic line has spiral shape.
According to a conventional hydraulic orifice, however, pulsation of the oil is reduced when passing through the oil hydraulic line. Therefore, the oil hydraulic line having suitable length should be formed. For this purpose, the oil hydraulic line of spiral shape should be formed and it may be difficult to form the oil hydraulic line.
In addition, since the outer case and the inner case are assembled by bending the forming portion formed at the outer case toward the inner case, a diameter difference between both ends of the outer case cannot be controlled within a predetermined error range. Since the oil hydraulic line is formed at the exterior circumference of the inner case, a part of the oil hydraulic line may be blocked when the forming portion is bent.
Further, when pressing the outer case on the head oil journal, an oil passage flowing the oil received from the hydraulic pump into the cylinder head and a supply hole of the outer case should be aligned. For this purpose, an additional tool should be necessary and it may be hard to assemble.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.